In the past, there has been known a technique of using in combination passive air conditioning for taking air into an indoor space from an outdoor space in order to control an air environment of the indoor space and active conditioning for controlling the air environment of the indoor space by use of an air conditioner (see document 1 [JP 9-14720 A]).
In the technique disclosed in document 1, a sensible temperature of a person in a building when a thermal environment of an outside of the building is reflected in a thermal environment of an inside of the building is predicted by use of a pseudo sensible temperature model, and a result of the prediction is used to determine whether to perform the passive air conditioning or the active air conditioning.
In the technique disclosed in document 1, to select the passive air conditioning (e.g., natural ventilation and forced ventilation) or the active air conditioning, calculation based on the pseudo sensible temperature model is conducted. This calculation requires a lot of parameters.
Therefore, to introduce this technique is considered to take a lot of work and time. Further, to make the pseudo sensible temperature model conform to a property of a human sensible temperature, it is considered that correction of parameters is necessary.
The technique disclosed in document 1 is effective to a building accommodating a lot of persons, but is not suitable for an indoor space accommodating a few persons such as a general residence. To apply the technique of document 1 to the indoor space accommodating a few persons, it is considered to use an index of comfort instead of the pseudo sensible temperature model.
However, the comfort greatly varies depending on physical conditions and activity histories of persons, feelings and psychological states of individuals. Hence, even when an index derived from calculation such as PMV (Predicted Mean Vote) is used for evaluation of comfort, there is no assurance that the air environment comfortable for persons-in-room is obtained.